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United States Patent |
5,177,317
|
Walker
,   et al.
|
January 5, 1993
|
Cable cutter assembly
Abstract
An explosive-type cable cutter assembly which includes a breech housing
having a central passageway formed in it and a first slot extending from
the exterior surface of the breech housing and opening into the passageway
and a second slot extending from the exterior surface of the breech
housing and opening into the passageway. The slots are each elongated in
the direction of the central axis of the breech and each include a
forwardmost edge and a rearwardmost edge. The cable cutting assembly also
incldues a threadable plug with an impact wall positioned forward of the
slots and radial ports extending from the exterior surface of the breech
housing into the passageway between the impact wall and the slots. The
cable cutter assembly further includes a piston cutter assembly having a
piston cutter adapted for travel within the passageway in the breech
housing. The piston cutter assembly includes an explosive cartridge with
attached piston cutter. The piston cutter includes a cutting edge and a
base end. The piston cutter has an axial length between the base end and
the cutting edge which is less than the axial distance between the impact
wall and the forwardmost edge of the slots and greater than the axial
distance between the impact wall and the rearwardmost edge of the slots.
The slots function both as a gas exhaust port and a cable receiving
eyelet. The slots are also offset to angle the cable with respect to the
piston cutter.
Inventors:
|
Walker; Stuart M. (Guntersville, AL);
Luttrell; Clyde K. (New Market, AL)
|
Assignee:
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Teledyne Industries, Inc. (Los Angeles, CA)
|
Appl. No.:
|
818541 |
Filed:
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January 9, 1992 |
Current U.S. Class: |
89/1.14; 114/221A |
Intern'l Class: |
B26B 005/12; B64D 001/00 |
Field of Search: |
89/1.14
114/221 A
|
References Cited
U.S. Patent Documents
745526 | Dec., 1903 | Rogers | 114/221.
|
2800868 | Jul., 1957 | Temple | 89/1.
|
2924147 | Feb., 1960 | Bohl et al. | 89/1.
|
2926565 | Mar., 1960 | Thorness | 89/1.
|
3024530 | Mar., 1962 | Haskell et al. | 89/1.
|
3320669 | May., 1967 | Chandler et al. | 89/1.
|
3701331 | Oct., 1972 | Harris, Jr. | 114/221.
|
3763738 | Oct., 1973 | Temple | 89/1.
|
4062112 | Dec., 1977 | Lake | 89/1.
|
4493240 | Jan., 1985 | Norton | 89/1.
|
4718320 | Jan., 1988 | Brum | 244/1.
|
4852455 | Aug., 1989 | Brum | 244/1.
|
Other References
Illustration of Impulse, Mark 23 Mod O Cartridge and accomanying sheet of
characteristics, Aug. 15, 1973.
Drawing sheet and exploded view of a cable cutter with the source of the
drawing being Mine Safety Appliances Company (date unknown).
Technical Manual "Aerial Gunnery Target Set A/A37U-36".
|
Primary Examiner: Brown; David H.
Attorney, Agent or Firm: Beveridge, DeGrandi & Weilacher
Claims
What is claimed is:
1. A cable cutter assembly, comprising:
a breech housing having a forward end, a rearward end, and an external
surface, a central axis extends between said forward and rearward end,
said breech housing having formed therein a passageway extending in the
direction of the central axis, said breech housing further including a
first slot extending from the exterior surface of said breech housing and
opening into said passageway and a second slot extending from the exterior
surface of said breech housing and opening into said passageway, said
first slot having a rearwardmost edge and said second slot having a
rearwardmost edge which is offset from the rearwardmost edge of said first
slot in a direction along the central axis of said breech housing; and
a piston cutter assembly which includes cutter adapted for travel in the
passageway formed in said breech housing.
2. A cable cutter assembly as recited in claim 1, wherein said first and
second slots are elongated in shape and said first slot has a major
diameter which is at least 0.20 of an inch longer than that of said second
slot.
3. A cable cutter assembly as recited in claim 1, wherein an impact wall is
provided at the rearward end of said breech housing and said central
passageway includes a first diameter section and a second, larger diameter
section positioned rearward of the rearwardmost edges of said slots and
forward of said impact wall.
4. A cable cutter assembly as recited in claim 1 wherein said piston cutter
assembly includes a piston cutter with a cylindrical base and a cup-shaped
forward end which defines a concave recess and a circular cutting edge.
5. A cable cutter assembly as recited in claim 1, wherein said first and
second slots are elongated and said first and second slots each have a
forwardmost edge which is essentially equally spaced from the forward end
of said breech assembly along the central axis of said breech assembly.
6. A cable cutter assembly as recited in claim 5 wherein said first and
second slots are elliptical in shape and said first slot has a major
diameter which is at least 0.20 of an inch longer than that of said second
slot.
7. A cable cutter assembly as recited in claim 1, further comprising a plug
and the rearward end of said breech housing including means for engaging
said plug, said plug including a forward end wall, and said piston cutter
having an axial length which is less than the axial distance between said
forward end wall of said plug and the forwardmost edge of said slots so as
to provide an exhaust conduit between an aft end of said piston cutter and
the forwardmost edge of said slots following a movement of said piston
cutter to the rear end of said breech assembly.
8. A cable cutter assembly as recited in claim 7 wherein said piston cutter
assembly includes a piston cutter with a cylindrical base and a cup-shaped
forward end which defines a concave recess and a circular cutting edge.
9. A cable cutter assembly as recited in claim 1, further comprising a
plug, sealing means, and a detonation cap, and wherein said passageway
extends through said breech housing and the rearward end of said breech
housing is releasably engaged with said plug and the forward end of said
breech housing is releasably engaged with said detonation cap, and said
sealing means being positioned between said breech housing and said
detonation cap so as to prevent a leakage of gases between said breech
housing and detonation cap.
10. A cable cutter assembly as recited in claim 9 wherein said detonation
cap and said plug are threadably engaged with said breech housing.
11. A cable cutter assembly as recited in claim 9 further comprising a
sealing member positioned between said plug and said breech housing.
12. A cable cutter assembly as recited in claim 1, further comprising a
plug, and said rearward end of said breech housing including means for
engaging said plug.
13. A cable cutter assembly as recited in claim 12, wherein said breech
housing includes a radial port positioned between said plug and
rearwardmost edges of said slots, and said port extending from the
exterior of said breech housing and opening into said central passageway.
14. A cable cutter assembly as recited in claim 13, wherein said central
passageway includes a first diameter section and a second, larger diameter
section which is positioned rearward of said first diameter section, and
said radial port opening into said second, larger diameter section of said
central passageway.
15. A cable cutter assembly, comprising:
a breech housing having a forward end, a rearward end, and an external
surface, a central axis extends between said forward and rearward ends,
said breech housing having formed therein a passageway extending in the
direction of the central axis, said breech housing further including a
first slot extending from the exterior surface of said breech housing and
opening into said passageway and a second slot extending from the exterior
surface of said breech housing and opening into said passageway, said
slots each being elongated in the direction of said central axis and each
including a forwardmost edge and a rearwardmost edge, said cable cutting
assembly further including an impact wall positioned rearward of said
slots and a radial port extending from the exterior surface of said breech
housing into said passageway between said impact wall and said slots; and
a piston cutter assembly having a piston cutter adapted for travel within
the passageway in said breech housing, said piston cutter including a
cutting edge and a base end, and said piston cutter having an axial length
between said base end and said cutting edge which is less than the axial
distance between said impact wall and the forwardmost edge of said slots
and greater than the axial distance between said impact wall and the
rearwardmost edge of said slots.
16. A cable cutter assembly as recited in claim 15 wherein said slots are
elliptical in shape with one of said slots having a major axis of a length
different than the other.
17. A cable cutter assembly as recited in claim 15 wherein said piston
cutter assembly comprises an explosive cartridge assembly which includes a
casing containing explosive material, said explosive cartridge assembly
being releasably secured to the forward end of said breech housing and
forward of said piston cutter when positioned in the passageway formed in
said breech housing.
18. An assembly as recited in claim 15 wherein said piston cutter includes
a concave recess with a rim section defining said cutting edge, and
wherein said piston cutter and explosive charge assembly are secured to
one another prior to detonation and adapted for separation following
detonation of said explosive charge cartridge.
19. An assembly as recited in claim 15 wherein said first and second slots
are essentially diametrically opposed and said first slot being axially
offset from said second slot.
20. A cable cutter assembly as recited in claim 15 wherein said impact wall
is defined by a forward wall of a plug member, said plug member being
releasably secured to the rearward end of said breech housing.
21. A cable cutter assembly as recited in claim 20 wherein said piston
cutter assembly comprises an explosive cartridge assembly which includes a
casing containing explosive material, said explosive cartridge assembly
being releasably secured to the forward end of said breech housing and
forward of said piston cutter when positioned in the passageway formed in
said breech housing.
Description
FIELD OF THE INVENTION
This invention relates to a cable cutter assembly. More particularly, this
invention relates to an explosive cable cutting assembly which is
particularly suited for use with an aerial gunnery target system.
BACKGROUND OF THE INVENTION
A variety of cable cutter systems for the purpose of cutting a cable or
line. For example, U.S. Pat. No. 745,526 illustrates an early rope cutter
system for cutting ropes used in Artesian well diggings. In U.S. Pat. No.
745,526, a weighted cutter housing is guided along the rope until reaching
the rope's end socket whereupon a circular cutting edge cuts through the
portion of the rope extending between a single aperture forming the guide
and the centrally positioned rope end socket.
U.S. Pat. Nos. 3,320,669, 3,763,738 and 4,493,240 are illustrations of more
recent explosive line cutting devices. U.S. Pat. No. 3,320,669 features a
line cutting device for cutting control lines on parachutes when the
supported load is expected to descend on a body of water. U.S. Pat. No.
3,320,669 includes a housing with end caps bolted thereto. The reference
also includes a piston with a large diametered base, a sloping
intermediate portion and a smaller diametered cylindrical projection. The
housing includes a pair of opposing elongated slots through which the
parachute line extends. Upon detonation of a charge forward of the base,
the piston is driven such that the cylindrical projection cuts through the
line and the shoulder portion of the piston contacts the intermediate
portion of the passageway formed in the housing to stop piston movement.
The chamber in which the base section travels includes a first radial vent
and a second vent positioned further downstream just forward of the
intermediate passageway. The first vent is for the exhausting of
pyrotechnic gases and the second vent is for venting compressed gas in
front of the piston's base section as it moves in the chamber.
U.S. Pat. No. 3,763,738 features a deep water explosive cutting tool which
includes a yoke-like housing through which cables extend. The yoke
includes guides for a spade-like cutter having a cylindrical rod received
within a passageway formed in an outer housing. A charge is received
within a bore formed at the free end of the cylindrical rod. Radial ports
are provided behind a sealing ring surrounding the cylindrical rod so as
to allow water to be introduced both in front of and behind the cutter for
equalizing the high pressure experienced in the deep water environment.
U.S. Pat. No. 4,493,240 illustrates another explosive parachute line
cutting device having a housing with a pair of diametrically opposed
circular holes formed at one end through which a parachute line extends.
An explosive charge system is positioned behind a blade with a circular
cutting edge. At the end of the housing is positioned an annular anvil
with a central aperture. The blade is forced forward so as to cut the
parachute line and subsequently is stopped upon contacting the anvil. In
this position, the blade's base is positioned forward of the holes and a
large, unsealed chamber is provided rearward of the charge to allow for
detonated gas exhaust.
An explosive cable cutter assembly designed for use with a towed aerial
target is shown in U.S. Pat. Nos. 4,718,320 and 4,852,455. U.S. Pat. No.
4,852,455 shows a chisel-shaped cutter while U.S. Pat. No. 4,718,320 shows
a clamping-type cutter assembly.
FIG. 12 of the present invention illustrates a previous embodiment utilized
in pre-existing aerial gunnery target systems (e.g. AGTS Tow Reel, A/A
37U-36). The system shown in FIG. 12 features axially aligned elongated
slots which provide for some play in the cable while being drawn in and
out by a cable reeling system. The piston cutter of the explosive
cartridge assembly illustrated in FIG. 12 is of an axial length which
results in the blocking off of the elongated slots following detonation.
Also, the breech assembly does not include an exhaust port for air
positioned in front of the cartridge. Instead, any air that does not
escape through the slots prior to passage of the cartridge is compressed
in the chamber area forward of the travelling piston cutter.
The prior art explosive charge cable cutting systems suffer from various
drawbacks including the failure to efficiently exhaust the gases produced
upon detonation of the charge. For example, in some of the prior art
embodiments, the resultant gases are exhausted out through the rear of the
charge assembly which lowers the driving pressure on the cutter. The prior
art also suffers from various problems such as detonation failures,
inadequate or incomplete cutting of cables, the unavailability of some of
the components for reuse, and difficultly in replacing components.
A failure of the cable cutter assembly to operate can be highly dangerous
for pilots involved in aerial gunnery target testing as the pilot is
forced to attempt a landing with the target still deployed. Since flight
runs are very expensive and there typically is only a limited number of
aerial gunnery targets available, it is also important that the aerial
gunnery target system and the cable cutter assembly associated therewith
be quickly readied for reuse following completion of a flight run. To
minimize expense, it is also desirable to reuse as many of the original
components of the cable cutter system as possible. The prior art systems
are not well adapted for reuse and fast assembly.
SUMMARY OF THE INVENTION
The present invention provides a cable cutter assembly which avoids the
above-noted deficiencies of the prior art. The present invention provides
a cable cutter assembly which is highly reliable, is very efficient at
cutting a cable, has reusable components, and is readily reassembled for
reuse. The present invention is particularly suited for use as a component
in a cable two reel assembly mounted on an aircraft. In such use, the
cable cutter assembly provides a means to sever the tow cable when, due to
a malfunctioning in the tow reel system, the deployed target or other
object cannot be retracted and stowed for a safe landing.
In so doing, the present invention features a cable cutter assembly having
a breech housing with a forward end, a rearward end, a central axis
extending between the forward and the rearward end, and an external
surface. The breech housing has a central passageway formed therein,
extending in the direction of the central axis. The breech housing further
includes a first slot extending from the exterior surface of the breech
housing and opening into the central passageway. A second slot extends
from the exterior surface of the breech housing and opens into the central
passageway. The two elongated slots are essentially arranged in
diametrically opposed fashion with respect to the essentially cylindrical
shaped breech housing. The first and second slots have a forwardmost edge
and a rearwardmost edge with the rearwardmost edge of the second slot
being offset from the rearwardmost edge of the first slot in a direction
along the central axis of the breech housing.
The cable cutter assembly also includes a piston cutter assembly having an
explosive cartridge with piston cutter. The piston cutter is adapted for
travel in the central passageway formed in the breech housing. The piston
cutter preferably includes a cylindrical base and a cup-shaped forward end
with a concave recess and a circular cutting edge. The shape of the
cup-shaped end of the cartridge is such that there is no concern for
alignment of the cutting edge which is a problem in some prior art
embodiments.
The first and second slots are elongated and the first and second slots
each have a forwardmost edge which is essentially equally spaced from the
forward end of the breech assembly along the central axis of the breech
assembly. Preferably, the first and second slots are elliptical in shape
and the first slot has a major axis which is preferably about 0.20 to 0.30
of an inch longer than the major axis of the second slot.
The cable cutter assembly also includes a plug, and the rearward end of the
breech housing includes means for engaging the plug. In a preferred
embodiment, the plug is threaded into a threaded bore formed at the rear
end of the breech housing and the plug includes a head member. A sealing
ring is positioned between the head of the plug and the rearward end of
the breech housing so as to form a seal when the plug is threaded into
position. The threaded plug provides easy access to the piston cutter for
the removal of the piston cutter prior to reuse of the breech housing. The
forwardmost portion of the plug forms an impact wall against which the
piston cutter impacts.
The breech housing includes at least one radial port and preferably two
diametrically opposed radial ports. Each radial port is positioned between
the plug and the rearwardmost edges of the slots, and each port extends
from the exterior of the breech housing and opens into the central
passageway. The central passageway includes a first passageway section and
a second, larger diameter passageway section which is positioned rearward
of the first passageway section. The radial port or ports open into the
second, larger passageway section of the central passageway. The
passageway includes a third passageway section which is positioned between
the first and second passageway sections and has a larger diameter than
the first passageway section and a smaller diameter than the second
passageway section. The threaded bore which receives the plug has a
diameter at the base of its threads which is essentially the same or
slightly less than the diameter of the second passageway section.
The piston cutter has an axial length which is less than the axial distance
between the forward end wall of the threaded plug (i.e., the impact wall)
and the forwardmost edge of the slots. This arrangement provides an
exhaust conduit between an aft end of the piston cutter and the
forwardmost edge of the slots following a movement of the piston cutter to
the rear end of the breech housing. Thus, the elongated slots function
both to define the cable passageway and to allow for the exhaust of the
gases produced by the detonation of the charge. This arrangement provides
a good manner of exhausting the resultant detonation gases as the
exhausting takes place immediately following the slicing of the cable and
not prior to contact between the piston cutter and cable. Therefore, loss
of detonation pressure is minimized.
The cable cutter assembly is particularly well suited for use in an aerial
gunnery target system. The breech housing is secured to framework
positioned rearward and below a cable guiding pulley. The cable extends
from the guiding pulley and through the slots in the breech housing and
through an exit location in the pod or housing for the reeling mechanism.
The exit location, guiding pulley position and breech housing position are
such that the cable when in a tensioned state slopes downwardly and
rearwardly in a direction away from the cutter's edge. The cable cutter
assembly described herein thus provides a means to sever a tow cable when,
due to a malfunctioning in the tow reel system, the deployed target or
other object cannot be retracted and stowed for a safe landing. The offset
rearwardmost edges of the slots cause the tensioned cable of a reeling
system to assume and maintain a position wherein it is inclined from the
vertical in a forward to rearward direction. This arrangement provides a
relatively more efficient (e.g., faster and cleaner) cutting of the cable
as opposed to extending the tensioned cable perpendicularly with respect
to the central axis of the cutting mechanism.
The second and third passageway sections are positioned just forward of the
impact wall of the plug such that, following the piston cutter's impact
against the impact wall, the piston cutter can be easily removed despite
outward deformation in the cutting edge. The diameter of the threaded bore
which receives the plug has a minimum diameter which is greater than the
diameter of the first passageway section and also preferably greater than
the diameter of the third passageway section. The second and third
passageway sections also avoid galling on the inside surface of the
passageway so that the breech can be reused many times. The position of
the larger diameter second and third passageway sections is particularly
useful in preventing galling of the passageway during rebound of the
piston cutter following impact. The impact wall is preferably axially
positioned at the rearward end of the second passageway section or
somewhere along the axial length of the second passageway section.
The breech housing includes a cylindrical threaded projection extending off
of a main body portion of the breech housing. The main body portion
extends rearwardly from the projection to the rearwardmost end of the
breech housing. The main body portion of the breech housing includes a
threaded exterior section extending between the forwardmost ends of the
slot and a declining shoulder portion which forms the base of the smaller
diameter threaded projection. The threads on the exterior of the main body
portion provide means for securement to supporting frame structure such as
the framework of a reeling pod in an aerial gunnery target system.
The threaded projection is designed for engagement with a detonation cap.
The detonation cap includes a cylindrical body with a threaded bore which
threadably engages the projection which extends off of the forward end of
the breech housing's main body portion. At the forward end of the cap's
forward bore is positioned a sealing member (e.g. an O-ring) which seals
the connection between the cap and projection. This sealed engagement is
also complemented by the close tolerance between the projector in the cap
so as to avoid any backflow of detonation gases out through the cap.
The detonation cap includes detonation means which comprises a detonator
member axially positioned just forward of the seal member. The detonation
member includes a small diameter central aperture for receiving the firing
pin of the piston cutter's explosive cartridge. The firing pin extends
from the forward end of the explosive cartridge base and is received
within the central aperture of the detonation member. The cap includes an
electrical connector at its forwardmost end which is sealed off to prevent
leakage of exhaust gases through the central aperture. The electrical
connector connects with an electrical line and an activation switch (not
shown).
Upon activation of the switch, the electrical current triggers the
detonation of the cartridge in a well known manner. Upon detonation of the
explosive in the cartridge of the piston cutter assembly, the explosion
causes the piston cutter with cutting edge to travel towards and through
the sloping cable while the gas between the moving piston and impact wall
is relatively moderately compressed and forced out the radial exhaust
ports. The piston cutter travels down the central passageway and impacts
the cable after travelling about 11/8 of an inch. The detonation produces
a pressure force of about 18 KPSI behind the piston. As the piston
accelerates down the passageway, it develops sufficient kinetic energy to
sever the cable. The gas pressure exerted on the piston aft end does not
provide essentially any cutting force, but rather the kinetic energy is
relied upon during cutting.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be more fully understood from the detailed
description given herein below and the accompanying drawings which are
given by way of illustration only, and thus are not, limitative of the
present invention and wherein:
FIG. 1 illustrates a top, planar view of the present invention with end
portions cut away for improved illustration;
FIG. 2 represents a cross-sectional, partially cut away view taken along
the mid-portion of that which is shown in FIG. 1;
FIG. 3 is a cross-sectional view of the breech housing shown in FIG. 1
taken along line III--III;
FIG. 4 is a cross-sectional view taken along IV--IV in FIG. 3 of the entire
periphery of the breech housing shown in FIG. 1;
FIG. 5 is a cut away view of that which is shown in FIG. 1 with the plug
removed;
FIG. 6 illustrates a cut away view of the detonation cap shown in FIG. 1;
FIG. 7 shows a piston cutter assembly suitable for use in the present
invention;
FIG. 8 shows a broken away view of that which is shown in FIG. 7;
FIG. 9 shows a cross-sectional view of the breech housing with the piston
cutter assembly in a pre-detonation state as well as the positioning of
the cable extending through the slots in the breech housing (one slot
shown);
FIG. 10 shows that which is shown in FIG. 9 except for the piston cutter
assembly being in a post-detonation state;
FIG. 11 shows a cut-away view of the present invention with the piston
cutter making initial contact with the sloped cable and the exhausting of
gas downstream from the piston cutter;
FIG. 12 shows a breech housing for a pre-existing cable cutter assembly;
and
FIG. 13 shows a cross-sectional view like that shown in FIG. 3 with
dimension lines A to O.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 illustrates a top planar view of the present invention with cut away
end portions. FIG. 2 presents a similar view of that which is shown in
FIG. 1, except for breech housing 14 being shown in cross-section. With
reference initially to FIGS. 1 and 2, cable cutter assembly 9 of the
present invention includes rear end plug 10 threadably received within
threaded bore 21 formed at the rear end 12 of breech housing 14. Sealing
member 16 (e.g. an O-ring formed of neoprene rubber) is positioned between
plug head 13 and rear end 12. Extending off of head 13 is threaded member
15. Threaded member 15 includes impact wall 17 at its forwardmost end and
is threadably received within threaded bore 21. Just forward of impact
wall 17 is positioned radial ports 18 and 20. Radial ports 18 and 20 open
into central passageway 22 which includes first passageway section 23,
second passageway section 24 and third passageway section 25. Radial ports
18 and 20 open directly into second passageway section 24 which is of a
larger diameter than third passageway section 25 and first passageway
section 23. Third passageway section 25 is of a larger diameter than the
much longer first passageway section 23.
Breech housing 14 includes main body portion 32 which is comprised of
rearward housing portion 34, ring shaped recess 30, and forward housing
portion 36. Forward housing portion 36 has threads 38 formed on its
exterior for securement to a supporting framework (e.g., 103 FIG. 10).
Extending forwardly off the front end of main body 32 is projection 40.
Projection 40 includes an inner wall surface 33 which defines reception
chamber 35 which opens into the forward end of central passageway 23.
Reception chamber 35 is of a slightly greater diameter than central
passageway 23 and includes gently sloping end 37. Inclined wall 39 is
positioned between the rearward end of projection 40 and the forward end
of housing portion 36. Projection 40 includes threads 41 which threadably
engage with threaded bore section 44 of detonation cap 43. Detonation cap
43 includes detonation member 46. When threads 41 of projection 40 are
threadably received within threaded bore section 44, sealing member 42 is
compressed between the forward end or rim 45 of projection 40 and interior
wall 49 (see FIG. 6) of detonation cap 43. Sealing member 42 can take a
form similar to sealing member 16. Sealing member 42, in combination with
strict tolerance requirements (e.g. 0.001 to 0.003 of an inch) between the
exterior surface of projection 40 and the interior surface of detonation
cap 43 helps prevent any back leakage of the gases produced in an
explosion described in greater detail below.
As shown in FIG. 6, detonation cap 43 includes electrical socket 51
extending for the forward portion of detonation cap 43. Electrical socket
51 includes a suitable electrical connection means such as pins or prongs
53 formed in sealing wall 55. Detonation member 46 includes pin aperture
54, the purpose for which is explained in greater detail below.
With reference now to FIGS. 1-5, slots 26 and 28 are formed as elliptical
slots with slot 26 being shorter than slot 28 by at least 0.20 to 0.30 of
an inch and more preferably about 0.25 of an inch. Breech housing 14 is
preferably fixed to a suitable framework structure through threads 38
being threaded into an appropriate threaded bore in a structural framework
(e.g. 103, FIG. 9). When fixed in position, shorter elongated slot 26 is
preferably the upper surface of the breech housing which is positioned
rearward and below a cable source, such as a cable guiding pulley
positioned above breech housing 14. Slot 28 is positioned diametrically
opposed to slot 26 and extends further rearward than slot 26, such that a
tensioned cable extending through both slots slopes in a downward and
forward to rearward direction. Slot 26 includes forwardmost edge 55 and
rearwardmost edge 56. Slot 28 includes forwardmost edge 57 and
rearwardmost edge 58. The forwardmost and rearwardmost edges can have a
smoothly curving wall extending from the exterior to the passageway to
avoid sharp edge contact with the cable and alternately, suitable liners
can be provided with the same shape of the elliptical slots.
FIG. 7 shows piston cutter assembly 59 with firing pin 60 extending from
cover 61 of explosive casing 62 and piston cutter 67 extending from casing
62. Firing pin 60, casing 62 and cover 61 define an explosive cartridge.
FIG. 8 shows a cut away view of that which is shown in FIG. 7. As shown in
FIG. 8, explosive casing 62 includes detonation material 63 centrally
positioned within casing 62. Casing 62 also include cylindrical projection
64 which is frictionally or adhesively secured within female reception
port 66 of piston cutter 67 having cutting rim 68. Cutting rim 68 is
circular and is defined by concave recess 69 extending inwardly into the
cylindrical body of piston cutter 67. Various depths and sloping
arrangements can be provided for surface 69 so as to provide the
appropriate sharp edge rim 68. In a preferred embodiment, surface 69
essentially defines a hemispherical recess having a radius of 0.16 of an
inch. Casing 62 has an external circumference which is slightly smaller
(e.g. 0.001 of an inch smaller) than wall surface 33 defining reception
chamber 35. An inwardly curved bead is provided at the rear end of casing
62 to correspond with curved surface 37. Piston cutter 67 has an external
diameter which is slightly smaller (e.g. 0.003 of an inch smaller) than
the surface defining passageway section 23. With this arrangement, piston
cutter 67 is properly guided during its travel within passageway 22. The
present invention also contemplates providing a sealing ring about the
exterior circumference of the piston to form a seal between the piston
cutter and passageway section 23. The seal can be formed of a low friction
material so as to facilitate travel within the passageway.
A piston cutter assembly which is suitable for the purposes of the presents
invention is an impulse cartridge manufactured by HAYES DIVERSIFIED
TECHNOLOGIES of California. Extending forwardly off cover 61 of casing 62
is firing pin 60. Firing pin 60 is received within pin aperture 47
centrally positioned in detonation cap 43. Threads 38 are threadably
received within framework structure 103 so as to properly orientate breech
housing 14 with respect to cable 100 extending through slots 26 and 28.
Cable 100 is typically comprised of steel filaments 101 surrounded by a
protective and encompassing covering 102 formed of a material such as
steel. Tension cable 100 is positioned in abutment with rearwardmost edge
58 of slot 28 and (although not shown) would also be in abutting
relationship with rearwardmost edge 56 of slot 26. FIG. 9 illustrates the
piston cutter assembly 59 in its pre-detonation state.
FIG. 10 illustrates piston cutter 67 following detonation of charge 63 in
casing 62 and following the piston cutter's separation from casing 62 and
passage through cable 100. As shown in FIG. 10, piston cutter 67,
following slicing through the cable 100, impacts at its forward edge 68
against impact wall 17 so as create a deformed front edge 106. As shown in
FIG. 10, passageway sections 24 and 25 are positioned just forward of the
deformed front edge 106. Passageway sections 24 and 25 are of a greater
diameter than the deformed front edge 106, thereby avoiding any galling on
the interior surface of central passageway 22, especially on rebounding of
piston cutter 67 after impacting wall 17. A portion of the cut off cable
is retained within the recess formed in the recessed defined by surface 69
in piston cutter 67 and thus further scratching or galling by the cut
edges of the segment of cable cut off by the cup-shaped rim is avoided.
Following impact, piston cutter 67 is easily removed as passageway section
24 and 25 prevent piston cutter 67 from being caught within the passageway
and plug 10 can be easily unthreaded as to gain access to piston cutter
67. Moreover, detonation cap 43 can be unthreaded and a new piston cutter
assembly 59 inserted in place of spent casing 62. The cap is then again
threaded in place such that the cable cutting assembly is again ready for
operation.
FIG. 10 also shows the positioning of aft end 105 of piston cutter 67
following impact with wall 17. In this position, aft end 105 is positioned
rearwardly of forwardmost edge 57 and 55 of slots 26 and 28, respectively.
Preferably, with the axial length between forward edge 57 and aft end 105
is about 0.20 to 0.22 of an inch. With such positioning of aft end 105,
exhaust ports (one designated 104) are formed on diametrically opposing
sides of breech housing 14 such that the exhaust gas resulting from the
detonation of explosive charge 63 is exhausted after piston cutter 67
slices through cable 100 and immediately before impact and for a period
following impact. Hence, slots 26 and 28 provide the dual function of
exhausting the gases resulting from the explosion and providing an
adaptable cable passageway.
Detonation is achieved by a suitable electrical signal being sent to
detonation cap 43 whereupon the electrical energy is relayed to firing pin
60 so as to trigger the detonation of the explosive material 67 contained
in casing 62. Upon detonation the resultant gases are directed forward so
as to separate piston cutter 67 from casing 62 and propel it towards cable
100. Backflow of the resultant gases is avoided due to the close tolerance
between casing 62 and reception chamber 35 and sealing member 42, as well
as the threaded connection of projection 40 and threaded bore 41.
FIG. 11 shows piston cutter 67 in its initial contact with tension cable
100. As shown in FIG. 11, circular edge 68 of piston cutter 67 is
essentially vertical while cable 100 is inclined with respect to the
vertical such that cutting takes place in sequential fashion. Cable 100 is
in contact with rearwardmost slot edges 56 and 58. The gases forward of
impact wall 17 and rearward of piston edge 68 are relatively moderately
compressed and then exhausted through radial ports 18 and 20. This
prevents any appreciable slowing down of piston cutter 67 in traveling
through cable 100. FIG. 12 shows a previously relied upon assembly with
breech housing 107 and piston cutter 110 which includes diametrically
opposed slots (one shown 108). The two diametrically opposed slots in FIG.
12 are of the same length and are not axially offset from one another such
that a cable passing therethrough is not inclined with respect to the
vertical. Also, piston cutter 110 used with breech housing 107 is depicted
schematically in dashed lines. Aft end 111 of piston cutter 110 is
illustrated in FIG. 12 to be forward of forwardmost end 112, 113 for slots
108 and 109 when cutting edge 114 of piston cutter 110 reaches its
rearwardmost position. The exhaust gases produced by the detonation are
retained at high pressure within the passageway forward of aft end 110.
The high pressure gases are gradually exhausted through the back end of
breech housing 107 due to a lack of close tolerances.
Although the present invention has been described with reference to a
preferred embodiment, the invention is not limited to the details thereof.
Various substitutions and odifications will occur to those of ordinary
skill in the art and all such substitutions and modifications are intended
to fall within the spirit and scope of the invention as defined in the
appended claims.
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